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<TITLE>Scheme 48 Manual -- Switches</TITLE>

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<EM>Scheme 48 Manual</EM> | <A HREF="s48manual.html#top_node">Contents</A> | In Chapter: <A HREF="s48manual_11.html">Command processor</A><BR>Previous: <A HREF="s48manual_16.html">Debugging commands</A> | Next: <A HREF="s48manual_18.html">Inspection mode</A>
<H2>Switches</H2>
<P>There are a number of binary switches that control the behavior of the
 command processor.
They can be set using the <CODE>,set</CODE> and <CODE>,unset</CODE> commands.
<P><DL><DT><B></B><DD><CODE>,set <CODE><I>switch</I></CODE> [on | off | ?]</CODE><BR>This sets the value of mode-switch <CODE><I>switch</I></CODE>.
    The second argument defaults to <CODE>on</CODE>.
    If the second argument is <CODE>?</CODE> the value of <CODE><I>switch</I></CODE> is
    is displayed and not changed.
    Doing <CODE>,set ?</CODE> will display a list of the switches and
    their current values.
<P><DT><B></B><DD><CODE>,unset <CODE><I>switch</I></CODE></CODE><BR><CODE>,unset <CODE><I>switch</I></CODE></CODE> is the same as
    <CODE>,set <CODE><I>switch</I></CODE> off</CODE>.
</DL>
<P>The switches are as follows:
<DL><DT><B></B><DD><CODE>batch</CODE><BR>In `batch mode' any error or interrupt that comes up will cause
    Scheme&nbsp;48 to exit immediately with a non-zero exit status.  Also,
    the command processor doesn't print prompts.  Batch mode is
    off by default.
<P><DT><B></B><DD><CODE>auto-levels</CODE><BR>Enables or disables the automatic pushing of a new command level when
    an error, interrupt, or other breakpoint occurs.
    When enabled (the default), breakpoints push a new command level,
    and <I>&lt;</I>eof<I>&gt;</I> (see above)
    or <CODE>,reset</CODE> is required to return to top level.  The effects of
    pushed command levels include:
<UL><LI>a longer prompt
<LI>retention of the continuation in effect at the point of errors
<LI>confusion among some newcomers
</UL>
    With <CODE>auto-levels</CODE> disabled one must issue a
    <CODE>,push</CODE> command immediately
    following an error in order to retain the error continuation for
    debugging purposes; otherwise the continuation is lost as soon as
    the focus object changes.  If you don't know anything about the
    available debugging tools, then levels might as well be disabled.
<P><DT><B></B><DD><CODE>inspect-focus-value</CODE><BR>Enable or disable `inspection' mode, which is used for inspecting
    data structures and continuations.
    <A HREF="s48manual_18.html">Inspection mode is desribed below</A>.
<P><DT><B></B><DD><CODE>break-on-warnings</CODE><BR>Enter a new command level when a warning is produced, just as
    when an error occurs.  Normally warnings only result in a displayed
    message and the program does not stop executing.
<P><DT><B></B><DD><CODE>ask-before-loading</CODE> <BR>If on, the system will ask before loading modules that are arguments
    to the <CODE>,open</CODE> command.  <CODE>Ask-before-loading</CODE> is off by
    default.
<BLOCKQUOTE><PRE>
&gt; ,set ask-before-loading
will ask before loading modules
&gt; ,open random
Load structure random (y/n)? y
&gt;
</PRE></BLOCKQUOTE>
<P><DT><B></B><DD><CODE>load-noisily</CODE><BR>When on, the system will print out the names of modules and files
    as they are loaded.  <CODE>load-noisily</CODE> is off by default.
<BLOCKQUOTE><PRE>
&gt; ,set load-noisily
will notify when loading modules and files
&gt; ,open random
[random /usr/local/lib/scheme48/big/random.scm]
&gt; 
</PRE></BLOCKQUOTE>
<P><DT><B></B><DD><CODE>inline-values</CODE><BR>This controls whether or not the compiler is allowed to substitute
 variables' values in-line.
When <CODE>inline-values</CODE> mode is on,
some Scheme procedures will be substituted in-line; when it is off,
none will.
<A HREF="s48manual_7.html">The performance section</A>
has more information.
<P></DL>
<P><P>
  
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